Note: Descriptions are shown in the official language in which they were submitted.
WO 2022/234259
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1
Power Tools and Battery Packs System
The invention to which this application relates is a power tool system which
incorporates two or more power tools, with at least some of the tools in the
system
required to operate with power supplied thereto at different rated voltages in
order
to operate safely and provide an optimum performance level. The rated voltage
for
each power tool in the system is provided from one battery pack connected
thereto
and which is mechanically and electrically connected to the power tool via a
battery
pack interface. Typically, the said battery pack can be selectively disengaged
from
the power tool housing in order to allow the battery pack to be used with
another
power tool or to be charged using a suitable charging facility and, when
charged, can
be reen.g,aged with the appropriate power tool to provide the appropriate
rated
voltage power level thereto.
The provision of power tools which are provided with a power supply from a
battery
pack rather than a mains electrical supply connected thereto by a cable, is
well-
known and power tools of this type, are generally referred to as portable
power tools
in that they can be provided to be operated at any location independently of
whether
or not there is a mains electricity power supply available. As such, power
tools of
this type have great attraction and the use of the same is widespread.
Conventionally, the portable power tool is provided with a battery pack which
is
specifically provided in a configuration to supply power at a particular rated
voltage
level to that particular power tool with which the same is provided and/or to
other
power tools which are of the same "power tool family", typically from the same
tool
manufacturer, in that the mechanical locations for the battery packs are the
same,
and the battery pack is provided to supply a particular predetermined rated
voltage
level required by the power tool to operate. However, increasingly portable
power
tools are provided which require different rated voltage levels of power in
order for
the same to operate and so, conventionally, a power tool owner who has a range
of
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power tools is also required to have a range of different types of battery
packs in
terms of different mechanical connection configurations to suit different
manufacturer's power tools and/or different electrical configurations and/or
power
cells to provide a particular rated voltage of power to particular power
tools. For
example, the power tools can be categorised in terms of the type of task which
they
perform, typically categorised as light, medium and heavy duty tasks and the
power
tools in each category operate at different rated voltage levels. Typically, a
low rated
voltage battery pack and a low rated voltage operable power tool are required
for
light tasks such as a power tool which is required to operate to perform
delicate tasks
such as engraving, soldering and/or where access is difficult to be gained to
reach
the point at which the work is to be performed.
The medium duty tasks typically are a range of "DIY" tasks which are generally
repetitive and require more robust work action and power tools so that a
medium
rated voltage battery pack and a medium rated voltage power tool combination
is
required to provide the required combination of power and endurance in order
to
perform the repeated tasks such as drilling of holes, or insertion and
tightening of
screws. For heavy duty tasks a higher rated voltage battery pack and higher
rated
voltage power tool combination is required as these work tasks are typically
more
demanding such as cutting thick or hard materials.
This can be expensive to the operator in that they have to purchase a battery
pack
and charger for each power tool. Furthermore, this can give rise to the risk
of
dangerous use of the power tool should the customer decide to try and save
costs
by adapting the battery pack which they already have to fit another
manufacturer's
power tool and/or to operate at a different rated voltage level than that for
which
the battery pack was intended. In order to avoid the risk of damage to the
power
tools and/or risk of a dangerous fire to the battery cells or power tool,
different
voltage battery packs and/or power tools are typically provided with a
mechanical
configuration intended to prevent the battery pack being fitted to a power
tool
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which has a different power rated voltage requirement than that which will be
provided by the battery pack if connected thereto and typically this is
ensured by
providing differences in the mechanical connection means at the battery pack
interface between the power tool and the battery pack in order to prevent the
deliberate or mistaken attempt to fit an incorrect battery pack to a
particular power
tool and thereby prevent an active electric connection being made. However,
these
mechanical features can be easily accessed and are typically located on the
outside of
the battery pack or power tool and so operators, either by accidental damage
or by
deliberate actions, may remove the mechanical features that prevent incorrect
connection or choose to modify the mechanical features on the battery pack or
power tool to allow an incorrect rated voltage battery pack to be fitted onto
a
particular power tool to extend the range of possible uses of the battery pack
across
more tools having different rated voltage requirements but the operator will
typically
have no understanding of the safety risks which are created and the
consequences
of which can be extremely dangerous.
As a result of this, more recent developments include the provision of first
and
second power tools as part of a power tool system with the tools operable at
different
rated voltages and the system also includes the provision of a battery pack
which
operates to provide power to a first of the power tools at a first rated
voltage and a
second battery pack which can be provided to operate in two configurations in
order
to allow the first rated voltage to be provided to the first power tool and a
second
rated voltage to be provided to operate the second power tool. Typically this
is
achieved by the provision in the dual voltage battery pack of two groups of
battery
cells and, by connecting these battery cells in parallel, a first power rated
voltage level
can be supplied from the battery pack and by connecting the groups of battery
cells
in series, a second rated voltage power level can be supplied from the same
battery
pack. Thus, typically, the groups of power cells connected in parallel, will
provide
the first lower rated voltage and the connection of the groups of power cells
in series,
will allow the provision of a power rated voltage which is double that of the
first
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rated voltage. The control of the particular rated voltage, which is provided
to the
power tool, is typically achieved by the selective positioning of mechanical
and
electrical switching means on the battery pack and the position of which is
defined
by mechanical means located on the power tool when engaged with the particular
battery pack interface, or may be achieved as a result of the provision of
mechanical
and electrical interaction of the connected power tool.
Thus, if, two power tools in the known system are of a type to be operated at
any of
two of light, medium or heavy-duty tasks, and the respective required rated
voltages
are a first rated voltage and a second rated voltage, which is twice the first
rated
voltage, then the two power tools, can receive the required rated voltage
power from
the same battery pack. However, this still means that power tools which
require the
third power voltage i.e., the remaining one of light, medium or heavy-duty
task
power tools, and which is most commonly the light duty task type of power
tool,
cannot be included in the system and will still require a separate battery
pack to be
provided and that battery pack will not be compatible with the other power
tools
which are required for the other two duty tasks.
A further problem is that the specific rated voltage required by the power
tools to
perform one of the light, medium and heavy duty tasks, may not be half or
double
the rated voltage required by power tools to perform the other two of the duty
tasks
and this can cause problems not only in the provision of a dual battery pack
to
provide power voltages at two rated voltage levels to different power tools
but also
with regard to any attempt to provide a second battery pack with a dual rated
voltage
capability as part of the same system. For example, the rated voltage of a
power tool
to perform a light duty task is not half that of the rated voltage required by
a second
power tool to provide the medium duty task and so a simple selection between
series
or parallel configuration of the connection of groups of power cells in the
battery
pack cannot always provide a solution.
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In addition, in order to ensure that both first and second battery packs of a
battery
pack system can be connected to a second power tool, then significant safety
risks
arise, as a battery pack which provides two higher rated voltage levels for,
for
example, medium and heavy duty task power tools, could be connected to another
power tool, for example a power tool to perform a light duty task, which
requires a
rated voltage power lower than the said higher rated voltages, resulting in
significant
safety risks such as overheating and fire. Conversely, should a battery pack
which
provides the first, lowest rated voltage of the system be connected to a power
tool
which requires the third, highest rated voltage then there is a significant
safety risk
that overheating and fire will result as the power tool demands a high current
from
an insufficient number of battery cells in the said battery pack. While
mechanical
features could be added to the battery pack interfaces to attempt to prevent
accidental connection being made, if the system requires both the first and
second
battery packs to be capable of providing a second, intermediate rated voltage
when
connected to, for example, a power tool which requires the second intermediate
rated voltage then this is not desirable or practical.
An aim of the present invention is therefore to provide a battery pack and
power
tool system which optimises the ability to allow power tools required to
perform
different tasks, such as for example, light, medium and heavy-duty tasks to be
provided with the required different rated voltages from a minimal number of
battery packs within the system, to thereby reduce the cost of the system,
increase
adaptability and functionality of the system. A further aim is to be able to
provide
these advantages whilst, at the same time, minimising the risk to the operator
and
opportunity for the operator to accidentally or deliberately manipulate the
battery
pack operation.
In a first aspect of the invention, there is provided a power tool and battery
pack
system including first and second battery packs, each of which is configured
so as,
when charged, to be able to provide power at two different rated voltage
levels, a
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plurality of power tools, each of said power tools operable when power at a
predetermined rated voltage level selected from at least three predetermined
rated
voltage levels is supplied thereto, a battery pack interface formed between a
said
power tools and a said battery pack when mechanically connected, said battery
pack
interface including electrical connection means for the transfer of power from
the
battery pack to operate the power tool, and wherein the possibility, and
selection, of
the supply of a predetermn. led rated voltage level from a said battery pack
to which
a power tool of the system is connected at that time to form the battery pack
interface, is determined by the configuration of an electrical circuit portion
located
within said power tool.
In one embodiment the said mechanical and electrical connection means at said
battery pack interface are common to each of the said power tools and battery
packs
in said system.
In one embodiment the electrical connection means at the said battery pack
interface
comprise a series of female sockets provided in one of the battery pack or
power
tool which receive a series of male pins or plugs provided in the other of the
battery
packs or power tools.
Typically, in order to allow the appropriate one of the predetermined rated
voltage
levels to be supplied from the appropriate battery pack connected to a power
tool at
an instant of time, the said electrical circuit portion provided within the
power tool
connects the operating drive system of the power tool to the pins or terminals
provided on the power tool at the battery pack interface, and the electrical
circuit
portion is configured so as to allow the appropriate predetermined rated
voltage
level to be supplied to the operating system of that power tool.
Typically, the configuration of the electrical circuit portion within a first
power tool
which is required to operate at the first predetermined rated voltage level is
different
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to the configuration of the electrical circuit portion of a second power tool
provided
to be operated at the second predetermined rated voltage level and furthermore
the
configurations of the electrical circuit portions of the first and second
power tools
are different to the configuration of the electrical circuit portion of the
third power
tool provided to be operated at a third predetermined rated voltage level.
Typically, the particular rated voltage level of power which is required for
operation
of each of the power tools in the system is predetermined at the time of
manufacture
of the power tool by the selection of the configuration of the electrical
circuit portion
within the power tool and thereafter the said configuration of the electrical
circuit
portion is unchanged during use of the power tool. In one embodiment the
electrical
circuit portion comprises electrical wiring and/or a circuit board located
within the
housing of the power tool.
Typically, therefore the battery pack interface formed between each of the
power
tools and battery packs of the system, has identical mechanical connection
means
and identical electrical connection pins and sockets. Typically, as a result,
in
accordance with the invention, no mechanical safety means arc required to be
provided to prevent particular power tools being mechanically connected to
certain
battery packs within the system.
In one embodiment, the system further includes a battery charger to allow a
charge
to be provided to the said battery packs in the system and typically said
battery
charger, when connected to the battery pack instead of a power tool, forms a
substantially identical battery pack interface as used by the power tools in
the system.
Typically the charger is compatible with and capable of charging all of said
battery
packs in the system.
In one embodiment the system incorporates two battery packs and a number of
power tools which can be selected from a range of power tools which are
operable
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at the three rated voltages which can be selectively provided from the said
battery
packs, with each battery pack in the system capable of providing at least two
of said
three predetermined rated voltage levels.
Typically each of the said battery packs is capable of delivering two of said
predetermined rated voltage levels with the said rated voltage levels which
are
provided determined by the configuration of the electrical circuit portion
within the
power tool which is connected to the battery pack at that instant of time.
Typically, each of the battery packs include a plurality of power cells, with
the
configuration and/or number of power cells within. a first battery pack
differing to
those provided in the second battery pack.
In one embodiment a first battery pack is capable of providing a first
predetermined
rated voltage level which is the lowest of the three predetermined rated
voltage levels
and a second predetermined rated voltage level which is intermediate in that
the level
is greater than the first but less than the third of the three predetermined
rated
voltage levels. Typically, a second battery pack of the system, is capable of
providing
two of the predetermined rated voltage levels, one of which is the said third
predetermined rated voltage level. Typically, the other predetermined rated
voltage
level provided by the second battery pack is the second predetermined rated
voltage
level so that the said second predetermined rated voltage level can be
supplied by
both the first and second battery packs.
For each of the battery packs the selection of whether a predetermined rated
voltage
level can be supplied, and, if so, which of two possible predetermined rated
voltage
levels which can be provided by the battery pack is to be supplied to the
power tool
connected thereto at an instant of time, is determined by the configuration of
the
electrical circuit portion located within the power tool which is connected to
the
battery pack at that instant of dine.
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In one embodiment, the third predetermined rated voltage level supplied by the
second battery pack is double the said second predetermined rated voltage
level.
Typically, for the second battery pack, the configuration of the respective
electrical
circuit portion of the power tools has the effect of groups of cells in the
battery pack
being effectively connected in series or parallel in order to supply the
particular one
of the two predetermined rated voltage levels.
In one embodiment, in the first battery pack, a selected number of a plurality
of
power cells are connected in a series circuit of at least two different forms
which
allow, in one form, the effect of all power cells being connected to deliver a
maximum possible combined voltage of the cells i.e., the second predetermined
rated voltage level from the first battery pack, or, in a second form, one or
more
power cells are bypassed or disconnected in order to deliver the first
predetermined
rated voltage level and again the selection of the particular form is made as
a result
of the configuration of the electrical circuit portion within the power tool
which is
connected to the battery pack at that instant of time.
Thus, in effect, the electrical circuit portion within the power tool is
dormant when
the power tool is not connected to the battery pack but, when connected to the
battery pack, the electrical circuit portion within the power tool is capable
of forming
part of and completing the electrical power supply circuit which extends
between
the battery pack and the connected power tool via the battery pack interface
should
the power tool be connected to an appropriate battery pack for the rated
voltage
power that is required.
In one embodiment, the electrical circuit portion of each of the power tools
in the
system, also acts as a safety system such that each of the power tools can
only
electrically connect to the power cells of a battery pack in a correct rated
voltage
delivery configuration and the electrical circuit portion is configured in the
power
tool in dependence upon the particular rated voltage which that power tool
requires
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and therefore this prevents an incorrect voltage demand being placed by a
power
tool upon either of the first or second battery packs which is especially
important if
the power tool has been incorrectly mechanically connected to a battery pack
which
is incapable of safely providing the rated voltage which that power tool
requires.
In a further embodiment, the safety system and/or electrical circuit portion,
are
located within the outer housing of the power tool and are therefore
inaccessible
from accidental access being gained and furthermore, if access is gained
deliberately
to try and reconfigure the electrical control means this will typically be
apparent or
in addition may be specifically rendered apparent by the provision of tamper
evident
means which will indicate if access has been gained in an unauthorised manner
to
the interior of the tool housing. This could be used as a deterrent such as
for example
rendering the warranty of the power tool void and so deter the incorrect usage
of
the power tool.
As a result of this inherent safety system within. the battery pack and power
tool
system as herein described, even if the first battery pack is mechanically
connected
to a power tool which operates at the third, highest, rated voltage and which
the first
battery pack is incapable of providing safely, no viable electrical connection
between
the battery pack and the power tool is possible as a result of the
configuration of the
electrical connection portion provided within that power tool, As a result,
the
operating system of the power tool, including the motor, cannot be provided by
power at an incorrect rated voltage level from the battery pack and so there
is no
risk to the user. Also, if the second battery pack is mechanically connected
to a power
tool which requires the first predetermined rated voltage level which cannot
be
provided from the second battery pack safely, the battery pack is not usable
with at
power tool.
In a further aspect of the invention there is provided a power tool and
battery pack
system including a plurality of power tools which can be selected from a range
of
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power tools configured to be operable at at least three different rated
voltage levels
and each of said power tools mechanically locatable with each of the battery
packs
and wherein the system includes two battery packs and at least one of the
battery
packs is selectively electrically connectable to said power tools to provide
the power
thereto at the correct one of the said three rated voltages for that power
tool.
In a further aspect of the invention there is provided a power tool and
battery pack
system including a plurality of power tools selectable from a range of power
tools
configured to be operable at at least three different predetermined rated
voltage
levels, a first battery pack capable of providing two of said rated voltage
levels and
wherein a second battery pack is provided which is capable of providing two of
said
voltage rated voltage levels and one of which is different to the said rated
voltage
levels provided by the first battery pack.
Typically therefore the first and second battery packs are capable of
providing the
same rated voltage level. Typically the said same rated voltage level is the
second,
intermediate, rated voltage level of the said three different predetermined
rated
voltage levels.
Typically the said same rated voltage is the second, intermediate, rated
voltage level.
In a further aspect of the invention there is provided a power tool and
battcry pack
system including a plurality of power tools which can be selected from a range
of
power tools configured to be operable at at least three different
predetermined rated
voltage levels, first and second battery packs to allow the provision of said
predetermined rated voltage levels and an electrical power supply circuit is
formed
between the battery pack power cells and the operating system of the power
tool
connected to the battery pack via a mechanically and electrically connected
battery
pack interface and wherein the said electrical power supply circuit is
selectively
completed by an electrical circuit portion located within the power tool and
which
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is configured, as a first step, to complete the said electrical power supply
circuit only
if the battery pack connected to the power tool at that time is capable of
providing
the particular predetermined rated voltage required to operate the power tool
and,
as a second step, if the first step is possible, to complete the electrical
power supply
circuit in a configuration to supply the said particular predetermined rated
voltage
level required to operate the power tool.
In a further aspect of the invention there is provided a power tool and
battery pack
system, said system including first and second battery packs, each battery
pack
capable of providing power at two different rated voltage levels, a plurality
of power
tools provided to be operable when power at a predetermined rated voltage
level
selected from at least three predetermined rated voltage levels is supplied
thereto, a
battery pack interface formed between mechanically connected one of the power
tools and one of said battery packs said battery pack interface including
electrical
connection means for the transfer of power from the battery pack to operate
the
power tool, said mechanical and electrical connection means at said battery
pack
interface common to each of the said power tools and battery packs in said
system
and wherein the possibility, and selection, of the supply of a particular
rated voltage
from a battery pack with which a power tool is connected to form the battery
pack
interface is determined by the configuration of an electrical circuit portion
located
within said power tool.
Specific embodiments of the invention are now described with reference to the
accompanying drawings wherein:
Figure 1 illustrates, schematically, a battery pack and power tool system in
accordance with one embodiment of the invention;
Figure 2 illustrates a further embodiment of the system in accordance with the
invention;
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Figures 3a-f illustrate the first battery pack and power tools in accordance
with an
embodiment of the invention;
Figures 4a-d illustrate the second battery pack and power tools in accordance
with
the embodiment of the invention; and
Figure 5 illustrates schematically, a possible configuration of an electrical
power
supply circuit in accordance with the invention.
Referring firstly to Figures 1 and 2, there are illustrated examples of
systems in
accordance with two embodiments of the invention.
In Figure 1, the system 2 comprises three power tools 4,6,8 and two battery
packs
10,12. In this embodiment, the first power tool 4 is provided to operate to
perform
a relatively low duty task, such as engraving, and in order to operate
requires a power
supply thereto, which in one embodiment, is a first predetermined rated
voltage level
of 12 Volts. The power tool 6 is provided to perform a medium duty task such
as,
for example, drilling, and in order to operate correctly, is required to be
provided
with power at a second predetermined rated voltage level, which in this
embodiment,
is 20 Volts. The third power tool 8 is provided to operate to perform a
relatively
heavy-duty task such as, for example, to perform a chain.saw cutting operation
and
is requir. cd to be provided with a third predetermined rated voltage level
powcr
supply to operate which in this embodiment is a rated voltage of 40 Volts. It
will
thus be appreciated that the second predetermined rated voltage level is
intermediate
the first and second predetermined rated voltage levels.
The power tools are provided to be portable and provided by power from the
battery
pack 10, or battery pack 12 which is selectively mechanically connected to the
housing 14 of the power tool. Thus, in accordance with the invention, the
system
includes the first battery pack 10 which is capable of providing power at the
first and
second predetermined rated voltage levels, 12 Volts and 20 Volts and the
second
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battery pack 12 is capable of providing power at the second and third
predetermined
rated voltage levels of 20 Volts and 40 Volts. Thus, in practice, the first
battery pack
is useable with either of the power tools 4 or 6 and the second battery pack
12 is
useable with either of the power tools 6 and 8 to provide power at the
required and
correct rated voltage level thereto when the battery packs are electrically
and
mechanically connected to form a battery pack interface 16 with the
appropriate
power tool.
Figure 2 illustrates a further example of a system in accordance with the
invention
in which, in this case, there is again provided the engraving tool 4 which is
to operate
at the first low duty predetermined rated voltage level, three power tools 6,
6' and
6" which arc all provided to be operable with the second predetermined rated
voltage
level in order to pet-form medium duty tasks such as drilling 6, driving
screws 6' and
power tool 6" operates to provide a sanding operation. Once again, there is
provided
a further power tool 8 which operates when supplied with power at the third
predetermined rated voltage level. It will therefore be appreciated that in
this
embodiment, there are a number of tools which operate at the second,
intermediate,
predetermined rated voltage level and in accordance with this invention, at
least two
of those tools can be available to be operated simultaneously by a first
operator
fitting one of the tools such as for example power tool 6 to the first battery
pack 10
to supply the second predetermined rated voltage level thereto and another of
the
power tools 6', or 6" to the second battery pack 12 to supply the second
predetermined rated voltage thereto as both battery packs are capable of
providing
that rated voltage level.
It will also be appreciated that the number of tools which are provided in the
system,
can be adapted by the user to suit their particular requirements, and may be
expanded
over time as long as the power tools in the system can be mechanically
connected to
the particular battery pack type in the system.
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Each of the power tools when mechanically connected to mechanical engagement
means on the battery pack forms a battery pack interface 16 and, at the same
time
as the mechanical connection, pins or plugs on one of the power tool or
battery pack
and sockets provided on the other of the power tool or battery pack are
electrically
connected together with the particular configuration of pins or plugs and
sockets
which are provided, typically being the same across all power tools and
battery packs
in the system. Typically, the pins or plugs are provided on the power tool and
the
sockets 18 are provided in the battery pack. Thus, the battery packs 10,12
which
each comprise a number of power cells, may be provided with part of an
electrical
power supply circuit therein which allows the connection of the power cells
and
wiring to the respective terminal sockets of the battery pack and in turn the
pins or
plugs on the power tool engage in the sockets when the battery pack interface
is
formed.
Each power tool is typically provided with a motor within the housing 14 which
is
provided to be provided with power at the required rated voltage in order to
drive
the work function of that power tool.
In accordance with the invention, the apparatus further includes an electrical
circuit
portion which is formed and located within the housing of each power tool and
connected to pins or plugs of the power tool and the control system for
operation
of the motor. If the rated voltage level of the power supply required by the
power
tool is capable of being safely provided by the battery pack to which the
power tool
is located at that time, the configuration of the electrical circuit portion
in the
particular power tool completes the electrical power supply circuit in a
configuration
which provides power to operate the power tool at the required rated voltage
from
the battery pack to the motor.
The configuration of the electrical circuit portion within the power tools,
differs
between tools in the system and with respect to the particular rated voltage
which
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the power tool is required to receive so that for example, the electric
circuit portion
of the first rated voltage power tools 4 is of a first configuration, the
electrical circuit
portion of the power tools 6,6',6"operable at the second predetermMed rated
voltage
level will be the same, second, configuration but will differ from the
configurations
of the electrical circuit portions of the tools, 4 and 8, and the third
configuration of
the electrical circuit portion of the power tools 8 to operate at the third
predetermined rated voltage level will differ from those of tools, 4 and
6,6%6".
In accordance with the invention, if the power tool 4, 6, 6',6" connected to
the first
battery pack 10 requires a first rated voltage level or the second
intermediate rated
voltage level then electrical power supply is possible from the battery pack
10 to that
power tool and the particular rated voltage of the power supply to that power
tool
is defined by the configuration of the electrical circuit portion within that
power
tool. However, if a power tool 8 which is required to be operable at the
highest
rated voltage which is not capable of being supplied by the first battery pack
10 then
automatically, it is not possible for that battery pack to provide any power
to that
power tool 8 as a result of the configuration of the electrical portion within
that
power tool. Equally, should the power tool 4 which requires the first rated
voltage,
be connected to the second battery pack 12 which is not capable of safely
providing
the first rated voltage, the configuration of the electrical circuit portion
within the
first power tool 4 prevents any power supply from the second battery pack 12
to
that tool 4. Thus, in accordance with the invention, for as long as the
predetermined
configuration of the electrical circuit portions within the respective power
tools is
maintained and unaltered, then it will not be possible for unsafe supply of
power
from the battery packs 10,12 to the power tools and furthermore, the
predetermined
configuration of the electrical circuit portion in each of the power tools
ensures that
when possible, the power is supplied to the said power tool at the correct
rated
voltage.
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17
Typically, the configuration of the electrical circuit portion in each of the
power tools
is predetermined in as much as it is defined by the provision of a circuit
board and/or
wiring withm the housing of the power tool at the time of manufacture of the
power
tool. In one embodiment, in order to prevent and/or deter attempts which may
be
made to alter the configuration of the electrical circuit portion, the same
can be
rendered inaccessible to end users of the power tool without the power tool
being
damaged and/or tamper evident means can be provided so as to show if an
attempt
has been made to alter the operating characteristics_of the power tool from
that
which were determined at the time of manufacture.
Figure 5 illustrates schematically, the manner in which an electrical circuit
20 for the
provision and control of power from a battery pack which is connected to a
power
tool at an instant of time, can be provided. The electrical circuit comprises
a portion
22 in the battery pack housing 24 which allows the connection of the power
cells of
the battery pack to a plurality of terminals, typically sockets, which are
exposed at an
interface 26 of the battery pack housing 24 and which connect to terminals,
typically
plugs or pins, which are selectively received in the terminals, which are
exposed on
the power tool housing 28 at the interface 26 such that the plugs and sockets
form
the electrical interface 26 between the power tool 28 and the battery pack 24.
Mechanical engagement means such as, for example, female guide channels and
male
elongate members and a locking mechanism, which can be slidably engaged, allow
the secure location of the battery pack with the power tool so that during
use, the
power tool and battery pack effectively form an integral unit and, as part of
the
sliding engagement of the battery pack with the power tool, the plugs and
terminals
are brought together into mechanical and electrical connection in an
appropriate
manner for operation of the power tool with that battery pack. In the power
tool
housing 28 the electrical circuit includes a portion 30 which connects the
power
received from the batteries in the battery pack to the motor 32 which, when
switched
on, and provided with an appropriate power supply, operates to perform the
working function of the power tool when switching means are moved to an on
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18
position. Intermediate the said portions 22 and 30 of the electrical circuit
of the
power tool and the battery pack, there is provided a connection portion 34
which is
configured within the power tool so as to ensure that the appropriate and safe
power
supply level required to operate the motor 32 of that power tool can only be
supplied
to the motor so that, for example, the configuration of the electrical circuit
connecting portion 34, is designed with respect to the particular power tool,
and the
particular battery pack so as firstly, to ensure that power can only be
supplied by a
battery pack which is of a form to be capable of safely supplyn. ig the power
and
secondly, to ensure that the power is supplied at the appropriate level.
A specific embodiment of the invention is now described and in accordance with
the invention, there arc provided two battery packs, a first battery pack 36
of a form
which is illustrated in Figures 3a-f and a second battery pack 38 which is
illustrated
in Figures 4a-d.
Referring firstly to Figures 3a-f, there is illustrated the first battery pack
36 with
terminals in the form of sockets 40 and mechanical engagement means including
a
release button 42 which, when pressed, releases the locking means and allows
sliding
action between the battery pack and the power tool housings to locate the same
and
when engaged, maintains the battery pack and power tool in mechanical and
electrical engagement Figure 3b shows the components located within the
housing
of the battery pack and it will be seen that there are provided five, 4 Volt,
power
cells 44a,b,c,d,e which are located in a row and these can be connected so
that all of
the cells are electrically connected and provide power which, in this
embodiment,
provides power at 20Volts as shown in Figure 3f or alternatively, only three
of the
power cells 44 c,d,e are connected to provide power at 12 Volts as illustrated
in
Figure 3e. In both configurations, the particular power cells which are
connected are
connected in series. As illustrated in. Figures 3d and 3e, the operation of
the battery
pack with only three power cells connected in series, means that the first
predetermined, 12 Volts, rated voltage level power supply is provided to the
motor
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32 and this is achieved with the plugs B1- and B2- of the terminals 46 of the
power
tool 48 connected to the sockets B1- and B2- respectively of the terminals 40
of the
battery pack so as to allow the connection of the three power cells 44 c,d,e
of the
battery pack. The particular connection of the plugs B1- and B2- in the power
tool,
in this configuration, is achieved by the configuration of the electrical
connection
portion 34 within. the power tool which connects to these two plugs and in
turn
allows connection of power to the motor.
As shown in Figures 3d and 3f, when it is required that the second, 20 Volts,
rated
voltage level power supply is provided from the battery pack to operate a
connected
power tool as shown then the electrical connection portion 34 in the power
tool, is
connected to the plugs B2+ and B2- of the power tool. These plugs therefore
locate
with the electrical socket terminals B2+ and 132- of the battery pack, which
therefore
allows electrical connection of the five power cells in series as illustrated
and
therefore the provision of the 20 Volts rated voltage level supply via the
electrical
connection portion 34 of the power tool to the motor 32 to operate the same at
20
Volts as required.
With regards to the second battery pack 38 then, as shown in Figures 4a and b,
similar mechanical location means 42 are provided to connect the battery pack
to
the power tool and the similar electrical socket terminals 40 are provided
thereon.
Within the battery pack housing, there are provided first and second groups 50
(50a,50b,50c,50d,50e), 52 (52a, 52b, 52c, 52d,52e), each of five 4V power
cells so
that each group is capable of operating to provide 20 Volts. In this case, the
battery
pack is rated at 2x20 Volts.
The interface 26 is identical across 12 Volts, 20 Volts and 40 Volt power
tools
between the first and second battery packs and therefore when connected to the
second battery pack 38, the electrical connection means portion 34 in a power
tool
which requires power at 20V to operate the motor 32, allows connection of the
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terminal plugs B2+, B1+, B2- and BI- of the power tool to the electrical
terminals
B2+, B1+, B2- and BI- respectively of the battery pack as shown in Figure 4c
which,
are connected to the first and second groups 50, 42 of cells so as to connect
the
groups in parallel which therefore allows a 20 Volts power supply to be
provided for
operation of the motor 32 of the power tool. As illustrated in Figure 4d, when
the
power tool which is connected to the battery pack is of a configuration and
has a
motor 32 which is required to operate at 40 Volts, then the electrical
connection
portion 34 within the power tool still uses the connection of the respective
plugs
B2+, B1+, B2- and Bl- with the electrical terminal sockets B2+, B1+, B2- and B-
1-
of the battery pack but, the electrical connection portion 34 of the power
tool differs
in that plug B1+ is connected to B2- so that the effect is that the first and
second
groups of power cells 50,52 of the battery pack are connected in series and
therefore
40 Volts is supplied to the power tool motor 32 which is required to operate
at that
voltage.
Thus, in accordance with the invention, there can be provided first and second
battery packs which are capable of providing a power supply to power tools of
a
type which are required to operate at any of three predetermined voltages and
in
which at least one of the power tools operating at one of the three
predetermined
voltages, can be used with either of the first or second battery packs to
receive the
required voltage for operation. Furthermore, the provision of the first and
second
battery packs and power tools as described, ensures that each of the battery
packs is
safely interchangeable for use with respect to at least two of the said power
tools in
the group of power tools to provide different voltages thereto but is
prevented from
being connected to provide power to another of the power tools in the said
group
of a different voltage so as to avoid any potential safety risk issues to the
end user.
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